This invention relates generally to steel converters and exhaust-gas treatment systems therefor and more particularly to an exhaust-gas treatment system of a sealed-type converter for operating in a fully sealed state relative to the outside air or a state close thereto.
More specifically, the invention concerns an exhaust-gas treatment system of the above stated kind which is provided with an emergency air admission valve device which is normally closed for normal operation of the converter and its exhaust-gas treatment system but operates instantaneously when there is an abrupt interruption of the converter operation to admit outside air into the hood of the exhaust-gas treatment system thereby to prevent the occurrence of abnormal negative pressure in the hood and related parts of the system.
As is well known, the operation of a converter comprises the three process steps of charging, blowing, and pouring. In the blowing step, as will be described in detail hereinafter, pure oxygen is blown through an oxygen lance or jet into molten metal in the converter to accomplish refining. The oxygen thus blown and carbon within the molten metal react to form a large quantity of carbon monoxide, CO, gas. Ordinarily, the converter is provided with an exhaust-gas treatment system for recovering this CO gas, which has commercial value, and preventing leakage of CO gas into the surrounding atmosphere.
The exhaust-gas processing system is coupled to the converter mouth by a hood. Since the converter is tilted about a horizontal axis for the charging and pouring steps mentioned above, the hood must be uncoupled from and recoupoled to the converter mouth at the beginning and end of each of these steps. Accordingly, the hood is provided with a skirt which can be raised and lowered for attachment to and detachment from the converter mouth. In a system wherein this skirt is adapted to fit tightly in a leak-proof or very nearly leak-proof manner against the converter mouth, the converter becomes one referred to herein as a sealed-type converter.
Normal operation of a sealed-type converter is efficient and economical. However, if the operation is suddenly stopped for some reason, a number of problematic situations, including danger of explosion and resulting damage and injury, arise as will be described in detail hereinafter in connection with one embodiment of the invention.